Refrigerating apparatus



March 2, 1943.

vR. M. SMITH REFRIGERATING APPARATUS Filed'Fen 27. 1940 2 Smets-sheet 1 \\\\m\\\\\\\\\\\ /IV ////7/ INVENTORQ '7?04 F SMI rfi.

ATTORNEYS.

BY l

Marh2,1943. M. SMITH 2,312,596

REFRIGERATING- APPARATUS Filed Feb. 27, 1940 2 sheets-sheet 2 .ws n ATTORNEY.;

pied by high pressure refrigerant.

Patented Mar. 2, 1943 REFmGEnA'rm'G APPARATUS Rolf M. Smith, Dayton, Ohio, assigner to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application February 27, 1940, Serial N0. 321.078

(Cl. 23o- 58) 6 Claims.

This invention relates to refrigerating apparatus and particularly to a. motor-compressor unit for refrigerating systems;

In motor-compressor units for refrlgerating systems and particularly compressors'of the singie-cylinder reciprocating type, enclosed within a sealed casing the interior of which is exposed to or forms a part of the high pressure portion of a refrigerating system, an extremely high load is placed on the eccentric member during the suction stroke of the compressor piston. This rection outwardly of its cylinder and into confines of a sealed high pressure chamber.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the aci companying drawings, wherein a preferred form high or peak load condition is created by moveg ment of the compressor piston outwardly of its cylinder into the area occupied by high pres-. sure refrigerant within-the lsealed casing. Due

to the unbalanced pressure condition between the interior of the sealed casing and the cylinder and the projected area of the piston head upon which the pressure within the casing can work, a temporary increase in wattage of the motor occurs during its rotation to actuate the vcompressor piston through its suction stroke.

Thus, my invention is directed generally to balancing the load condition of a compressor on its operating motor to thereby render a motor of a sealed motor-compressor unit more eillcient.

An object of my invention is to provide an improved sealed motor-compressor unit for use in refrigerating systems.

'Another object of my invention is to provide a sealed motor-compressory unit of the type wherein a piston reciprocates within a cylinderlocated within a sealed casing which casing is under compressor discharge pressure orforms a part of the high pressure side of a refrigerating 'system with means for balancing the `loa thereof placed upon the motor. In carrying out the foregoing objects -it is further object of my invention to provide' a sealed motor-compressor u'nit of the type wherein a motor is directly connected with the compressor by an eccentric and Scotchyoke forming .elements for reciprocating a piston in a cylinder with means which aids thev motor in movingthe piston outwardly relative to the cylinder into the area within the sealed casing occu- More speclcally. it is an object tion to provide a spring having one of its -ends Y connected to the casing of a sealed motor-compressor unit"and its other end connected to 'a member of a Scotch yoke connection between an eccentric formed on the motor shaft and a re-v 'clprocating piston which spring exerts .a force tending' to old movement of the piston in a diof the present invention is clearly shown'.

In the drawings: f Fig. 1 is a transverse vertical a sealed motor-compressor lunit having my invention embodied therein;

Fig. 2 is a horizontal sectionof the unit shownv in Fig. 1 and is taken on the line 2--2 thereof; and 4 Fig. 3 is a horizontal sectional view taken on the line 3--3 of Fig. 1 illustrating the connection of the motor with the compressor` of the .unit and showing the compressor piston at the end of its suction stroke.

Referring to the drawings, for illustrating my invention, I have shown in Fig. 1 thereof a sealed motor-compressor unit adapted to form a .partof a closed ref rigerating system (not shown) and the interior of which unit is subjected to compressor discharge pressure or forms a part ofthe I -high pressure side of the system. The unit includes a cast metal spider-like main frame II provided with. a central vertical bore,'the wall pression therein for a purpose to be hereinafter of which forms a bearing I2 for a shaft I3 dis-v posed therein. Frame II is also provided with an upstanding wall I4 concentric with the shaft v bore (see Fig. 2) and which wall is adapted to be secured in any suitable or conventional manner to a dome I5. The top surface of the perforated horizontal bottom portion of frame II is'undercutas at I6 to provide a trough-like dedescribed. A'portion of the bottom of frame II is provided with a at plane surface I1 disposed perpendicularly to the shaft bore. The upright wall I4 y,of frame II receives and supports a motor stator generally represented by the reference character I8 and having windings con-l windings with a suitable source of electric cur.`

rent. A motor rotor, generally represented by the reference character 2l and located within` the motor stator I8; is rigidly secured toa metal member 2,8- suchas byjbeingtightly pressed I thereon.

which receives the upper end of shaft I 3 and is- Metal member 28 has a central bore the sectional view of y preferably rigidly secured to the shaft by being tightly pressed thereon. Rotation of motor rotor 24, therefore, rotates member 26 and shaft I3 due to the rigid connection of member 26 with rotor 24 and with shaft I3. Metal member 26 is hollowed out as at 21 to loosely 't over and surround the upper wall portion 26 of the shaft bearing I2. A thrust washer 29 is disposed between the top end of bearing portion 28 andthe inner horizontal surface of the hollowed out part 21 of member 26. Washer 23 is provided with a groove or a plurality of grooves 3| in its face which engages the top of bearing portion 26 for 'a purpose to be hereinafter described. Shaft I3 has an integral enlarged lower portion 33 provided with an integral round shaft extension 34 which has its vertical axis offset horizontally relative to the vertical axis of shaft I3 soras to serve as an eccentric portion which rotates' around the vertical axis of the shaft bore.

The eccentric portion or shaft extension 34 is adapted to operate parts of a compressor located below the motor of the unit. The compressor portion of the unit is contained within the lower casing 22 and includes a housing 36 having a horizontally disposed cylinder 31 formed therein. Housing 36 is provided with a at or plane top surface that registers with and is secured in sealing engagement to the plane bottom surface I1 of the main or spider-like frame II by bolts or the like 38 (see Fig. 2). A piston 4I located within cylinder 31 of housing 36 is welded or otherwise suitably secured to a horizontally disposed collar-like element 42 provided with aligned elongated openings 43 for receiving the eccentric or shaft extension 34. A horizontally disposed slider 44 flts within collar 42 ing of same, by a connection extending through dome I5 near the top thereof.

A hollow inverted cone-shaped element 56 having a cover 51 is secured to the bottom of eccentric or shaft extension 34 of shaft I3 by a screw 58. It will be noted that the cone-shaped element 56 has its vertical axis disposed in alignment with the axis of the central bore in frame II or with the axis of shaft I3. Since the interior of the unit forms a part of the high pressure portion of .a refrigerating system a body of lubricant will, as is conventional, becontained in the bottom ,of the sealed enclosure. The lower portion of inverted cone-shaped element 56 is adapted to project into the body of lubricant and this cone-shaped element is therefore utilized for circulating the lubricant to operate parts of the unit as is fully disclosed and described in my copending application Serial No. 297,148 filed September 29, 1939. A box 6 I, having an opening 62 in its top wall for receiving a portion of the element 56, is mounted below the element 56 in the body of oil in the sealed unit and is/secured to housing 36 by a bracket 63 and a screw 64.

The bottom of box 6I is in the form of a screenA 66 which serves to strain foreign matter out of and is provided with a round vertical opening 'i which receives the eccentric shaft extension 34.

The outer wall of slider 44 is cylindrical in crosssectional contour and forms a bearing for the inner cylindrical surface of collar 42. 'I'he construction and arrangement of the elements of the connection between the eccentric or shaft extension 34 and the piston 4I form a Scotch yoke connection. The elements of the Scotch yoke connection are held in place relative to the eccentric or shaft extension 34 by virtue of the piston 4I fitting 'within cylinder 31 of housing 36. The head of the compressor comprises a plate 46 having suitable or conventional inlet and outlet valves carried thereby and a head plate 41 secured to the housing 36 over valve plate 46 by bolts or the like. A conduit 5|,having its one end sealed to the wall of casing 22 and its other end sealed to housing 36 has a muiller device 62 interposed lbetween its ends and is utilized for drawing gaseous refrigerant into the compressor cylinder 31. Refrlgerant compressed by the pis- .ton 4I in cylinder 31 is discharged through the suitable check valve in or on valve plate 46 into the head plate 41 where it is caused to iow through a series of elongated communicating passages 63 provided in the housing 36. The compressed refrigerant is directed from the innermost passage 53 through a porthole 54 registering therewith and extending through the bottom wall portion of frame `II and is discharged into the sealed casing at a point above the bottom of the frame. Passages 53 serve to mume the dischargeof compressed' refrigerant from cylinder 31 and the compressed refrigerant contained in the sealed enclosure may be directed to a point exteriorly thereof, to permit cooling and liquefythe oil to be picked up by element 56 for circulation to operating parts of the unit. Oil circulated upwardly through suitable openings in and grooves around shaft I3 by element 56 is circulated outwardly from the top of bearing I2 through the groove or grooves 3| in washer 29 and thereafter flows downwardly around bearing I 2. Some of this oil finds its way into the trough or depression I6 in the top surface of the bottom of frame II. A hole 61 provided in frame II and extending from the trough I6 communicates with a hole 66 provided in housing 36. The registering holes 61 and 68 lead to the cylinder 31 and theseholes direct oil from the trough I6 onto the piston 4I andthereby lubricates the wall of cylinder 31 during reciprocation of the piston therein.

In lorder to carry out the objects ofl the present invention I provide an integral projection or ear 1I on the side of collar-like element 42 opposite the side thereof to which piston 4I is secured. A similar projection or ear 12 is formed on a metal piece which is welded or otherwise suitably secured to the inner vertical side wall surface of the lower casing 22. 'I'he projections or ears 1I and 12 are each apertured as at 13. A coil spring 14 has its one end 15 received in the aperture 13 of ear 12 and has its other end 16 received in the 'aperture of ear 1I. 'I'his spring 14 exerts a pulling force upon the collar 42 and consequently upon the piston 4I secured thereto. In the operation of the compressor portion of the unit by the motor thereof the eccentric or extension 34 of shaft I3 revolves in a. circle around the vertical axis of shaft I3. This rotation of eccentric 34 causes reciprocation of slider 44 within collarlike element 42 during movement of element 42 in a direction to and from housing 36 to reciprocate the piston 4I within the cylinder 31. As before stated, reciprocation of piston 4I and particularly movement thereof in a direction outwardly of cylinder 31 causes evaporated or gaseous refrigerant from an evaporator of a refrigerating system to be conveyed through pipe 5I and muliler 52 through a suitable or conventional suction inlet valve into the cylinder 31.v Movement of piston 4I in a direction into the cylinder 31 compresses the refrigerant previously drawn conventional outlet valve associated with the plate into the passage provided therefor in head 41. The passage in head 41 communicates with the series of passages or passagewaysI 53 and hole 54 to direct the compressed' refrigerant into the sealed enclosure formed. by the dome l and lower casing 22. The reduced pressure within cylinder 31, created by movement of piston 4| in a direction outwardly thereof, together with the high pressure existing in the sealed unit and acting on the relatively large area of the piston usually oers a great amount of Vresistance to movement of the piston 4I outwardly of cylinder 31. It has been found that this resistance is of such intensity as to ordinarily create the maximum load condition on the motor, and this load condition is greater during the suction stroke than during the compression stroke of piston 4i. Although this high load condition occurs during only a-short period of a complete revolution o the motor rotor, it is, nevertheless, detrimental to eihcient operation of the motor in that the wattage of the -electric current required for the motor at this period is increased. The short periodof high load condition creates an unbalanced condition of operation of the unit and, furthermore, places an abnormal load in one direction on the bearings or operating parts of the Scotch yoke connection between the motor shaft and the piston. These defects in a unit of the type disclosed areA eliminated by the incorporation in the unit of my improvement which consists of the spring 14. Spring 14 is stretched when the piston moves into cylinder 31 and therefore exerts a pulling force on collar-like member 42 and piston 4l when the piston moves in a direction outwardly of cylinder 31and into the confines .of the high pressure within the sealed chamber. This pulling force of spring 14 overcomes the pressure of the high pressure 'refrigerant in the unit acting upon the piston 4I and thereby minimizes or destroys the resistance toY movement of the piston Il into the confines of the high pressure chamber during its suction or intake stroke. 'I'he spring 14 balances the load on the bearings of the Scotch yoke connection and eliminates the short period high or peak load condition described'to thereby reduce the high wattage required by the motor of the unit.

tor including a shaft having an eccentric portion, said compressor including a cylinder and a piston disposed therein, means connecting said piston to said eccentric portion of said shaft for.

- reciprocating the piston within said cylinder when said'motor is operated,'and means having a part attached to said connecting means and another part thereof attached to said casing forapplying force to said piston at least in the dil rection of movement of the piston outwardly relative to its cylinder. j

2. A sealed unit comprising, a casing having a motor and a compressor directly connected to l said motor mounted therein, said casing being under compressor discharge pressure, said mo# tor including a shaft havingan eccentric portion, said compressor including a cylinder and a piston disposed therein, means connecting said piston to said eccentric portion of said shaft for reciprocating the piston within said cylinder when said motor is operated, and a coil spring` having one of its ends 4attachedto said connecting means and having its other end attached to said casing for applyingforce to said piston at least in the direction of movement of the piston outwardly relative to its cylinder.

3. A sealed motor-compressor unit including a casing, said casing being under compressor discharge pressure, a main frame within said casing and supported therefrom, said main frame having a vertical bore forming an elongated bearing, a shaft within ysaid bore, a motor stator supported upon said main frame in the upper part of said sealed casing, a motor rotor secured to the upper end of said shaft for rotating same, said shaft having an eccentric portion below said main frame, a compressor 'secured to and depending from said main frame, said compressor including a cylinder extending perpendicularly to said motor shaft and in horizontal alignment with said eccentric portion thereof, a piston disposed within said cylinder, means connecting said piston to said shaft eccentric portion for reciprocating the piston within said cylinder when the motor is operated, and means applying force to said piston at least in the direction of movement thereof outwardly relative to itscylinder.

4. A sealed motor-compressor unit including a casing, said casing being under compressor discharge pressure, a main frame within said casing and supported therefrom, said main 1 frame having a vvertical bore forming an elonsimple in nature and is of infinitesimal expense to thus permit its incorporation in a sealed unit without complicating the structure and without materially increasing the cost thereof.

dicularly to said motor shaft and' in horizontal v alignment with said eccentric portion thereof,

a piston disposed within said cylinder, means connecting said piston to said shaft eccentrir portion for reciprocating the piston within said cylinder when the motor is operated, and means having a part attached'to said connecting means and another part thereof attached to said casing for 'applying force to said piston at least in the direction of movement thereof outwardly relative to its cylinder.

5.l A sealed motor-compressor unit including al casing, said casing being undercompressor .discharge pressure, a main frame within said casing and supported therefrom. said main frame having a vertical bore forming an elongated bearing, a shaft within said bore, a motor stator supported upon said main frame in the upper part of said sealed casing, a motor rotor secured to the upper end of said shaft for rotating same, said shaft having an eccentric portion below said main frame, a compressor secured to and depending from said main frame, said compressor including a cylinder extending perpendicularly to said motor shaft and in horizontal alignment with said eccentric portion thereof, a piston disposed within said cylinder, means connecting said piston to said shaft eccentric portion for reciprocating the piston within said cylinder when the motor is operated, and la coil spring having one of its ends attached to said connecting means and having its other end attached to said casing for applying force to said piston at least in the direction of movement thereof outwardly relative to its cylinder.

6. A sealed unit comprising, a casing having a motor and a compressor directly connected to said motor mounted thereinsaid casing being under compressor discharge pressure, said motor including a shaft having an eccentric portion, said compressor including a cylinder and a piston disposed therein, means connecting said piston to said eccentric portion of said shaft for reciprocating the piston within said cylinder when said motor is operated, a coil spring disposed within said casing with its one end attached to said connecting means and its other end attached to said casing, and said spring applying force to said piston at least in the direction of movement thereof outwardly of its cylinder into said casing for overcoming high pres- `sur within the casing acting on the projected area of the piston head.

ROLF M. SMITH. 

